This invention relates generally to an optical measuring device for a line of sight projection of an angle measurement from a reference surface. In particular, the device of this invention comprises an optical plumbing device for determining verticality from a point on a reference surface to a point on a surface vertically and spatially displaced from the reference surface.
In the past, the conventional device for determining verticality has been the plumb line. The plumb line includes a line or cord having one end fastened to a weight or plumb bob. To transfer a point on one surface to a point on a second surface, vertically and spatially displaced from the first surface, the line is held or supported such that the plumb bob is freely suspended at the end of the line. If a point is to be transferred from the lower of the two surfaces to the upper, the line is adjusted such that the plumb bob is positioned over the point on the lower surface. The point on the upper surface where the line intersects is the transfer point. Generally, this operation is a two man operation unless the spatial distance between the two surfaces is short. A device that would permit a plumbing operation to be accomplished by a single person is to be desired.